PROJECT SUMMARY/ABSTRACT Companies are increasingly marketing mobile technologies as FDA-cleared medical devices, yet we do not know the consequences of these devices on healthcare utilization, cost, and outcomes. Recently, Apple released the Apple Watch Series 4 as an FDA-cleared medical device. The device includes an alert for the presence of atrial fibrillation (AF) and allows anyone to monitor their heart rhythm for the presence of AF. Apple has an enormous global audience, and the number of people who will use this (and other similar devices) to self-diagnose or monitor AF will be substantial. On one hand, the device may allow new diagnoses that result in treatment, improved quality of life, fewer AF related complications. On the other hand, the device may result in false positives in otherwise healthy people, resulting in more testing and treatments with associated harms. In fact, the U.S. Preventative Task Force recommends against routine surveillance for AF in the general population, citing lack of evidence and possible harm. We have an urgent need for a population-based infrastructure to ensure that technologies entering the market as medical devices are beneficial and safe. The overall goal of this project is to measure the uptake and effect of the Apple Watch 4 release on healthcare utilization among first-time and known AF patients. Dr. Shah is an early stage investigator with a K08 Career Development Award from the NHLBI. As part of the K08, she has developed a detailed cohort of contemporary AF patients, including clinical notes. Along with a team, she will use real world data, as proposed by the FDA, to generate evidence about risks and benefits of consumer-driven AF detection. She will use natural language processing to leverage the notes and identify AF patients who seek care due to the medical device, and evaluate downstream healthcare utilization, such as additional clinic visits, cardioversions, additional remote monitoring, and cost. The goals of this project will be accomplished through the following Specific Aims: 1) Estimate the proportion of first-time AF patient visits attributable to a mobile device before and after FDA clearance of the Apple Watch 4, and characterize device accuracy and downstream healthcare utilization in this population; and 2) Evaluate healthcare utilization patterns among prevalent AF patients who use mobile devices with AF alerts. In 2017, Apple sold 17.7 million smart watches, in a device market that continues to grow. Extrapolating from prior annual sales and conservatively assuming a 5% increase in users each year, almost 60 million people will have an Apple Watch by the end of 2020 (not accounting for non-Apple devices with similar functionality). Thus, even in this short period of time, uptake will be substantial and warrant immediate feedback. The results of this project will provide preliminary data for a long-term, multicenter study that evaluates the benefits (improved quality of life, fewer strokes) and harms (increased treatment complications, increased cost) of consumer-driven AF detection.